Serological Responses to Target Streptococcus pyogenes Vaccine Antigens in Patients With Proven Invasive β-Hemolytic...

Area of Science:

• Immunology
• Microbiology
• Vaccinology

Background:

• Rising incidence of invasive β-hemolytic streptococcal (iBHS) infections necessitates preventative strategies.
• Vaccination against Streptococcus pyogenes (Strep A) could be enhanced by cross-species immunity against Streptococcus dysgalactiae subspecies equisimilis (SDSE) and Streptococcus agalactiae (GBS).

Purpose of the Study:

• To assess antibody responses to Strep A vaccine candidate antigens in patients with invasive infections.
• To investigate potential cross-species immune responses relevant for vaccine development.

Main Methods:

• Prospective observational study of adult patients with iBHS infections (Strep A, SDSE, GBS).
• Assay of antibody responses to 6 Strep A candidate antigens using acute and convalescent sera.
• Defined serological response as an increase of >0.2 log10 AU/mL.

Main Results:

• Strep A patients showed significant antibody responses to all 6 tested antigens.
• SDSE patients had significant responses to streptolysin-O, S. pyogenes adhesion and division protein, and C5a peptidase (ScpA).
• GBS patients showed significant responses to ScpA only.

Conclusions:

• Invasive Strep A infection elicits robust antibody responses to candidate vaccine antigens.
• Significant responses to C5a peptidase in SDSE and GBS patients suggest potential for cross-species protection.
• Further research is needed on cross-species protection and vaccine efficacy correlates.